Inductance system



L. A. GEBHARD INDUC'IANGE SYSTEM Filed Dec. 22, 1928 M2 Sheets-Shet 1April 8, 1930.

April 8, 1930. L. A. GEBHARD v 1,753,408

INDUCTANCE SYSTEM Filed Dec. 22, 1928 v 2 sheets-sheet 2 lll II ToSource o AQ.

@ JEsAFormgr Patented Apr. 8, 1930 UNITED STATES- PATENT OFFICE LOUIS A.GEBHARD, OF WASHINGTON, DISTRICTOF (IIOLUIMIIBIA, ASSIGNORTO WIREDRADIO, INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE INDUCTANCESYSTEM Application filed December 22, 1928. Serial No. 327,988.

My invention relates to inductance systems in general and morespecifically to inductance systems employed in thermionic tubetransmitters. An object of my invention is to provide an inductancesystem for high frequency transmitters of the type employing thermi onictubes having the anodes thereof cooled by a circulatory liquid.

Another object of my invention is to provide an inductance systemwherein the high frequency output circuit includes the circulatorysystem of the cooling fluid.

Still another object of my invention is to provide an inductance systemwherein the cooling fluid circulates through the high frequencyinductance of an electrically balanced thermionic tube transmittingsystem.

A better understanding of the inductance system of my invention can behad by referring to the specification following and to the accompanyingdrawings wherein:

Figure 1 is a diagrammatic illustration showin the inductance system ofmy invention an Fig. 2 is a schematic circuit diagram showing theinductance system of my invention.

In transmitting systems employing ther mionic tubes having their anodescooled by 80 a circulatory liquid it is essential to efliciency that thelosses of high frequency energy in the cooling system be reduced to aminimum.

With the connection of the cooling fluid to and from the thermionictubes by means of an insulated length of tubing or hose, con! siderableloss of energy occurs. This is due primarily to the high potential ofhigh frequency energy concentrated at the points of connection. Theinductance system of my invention reduces these losses to a minimum andin addition provides many, advantages, as will appear from thespecification follow- The cooling liquid is associated with thermionictubes 1 and 2 by means of helical coil 5.

Coil 5 comprises a length of metal having dual passage for conveying thecooling fluid to and from the respective tubes. C011 5 is hereinillustrated as comprising individual I lengths of metal tubing which areplaced parallel to each other and positioned in this manner by weldingor other suitable means. This provides a single electrical conductor anda dual passage for the circulating liquid. The circulating liquid isassociated with coil 5 by means of connectors 5 and 5 which conduct theliquid to and from the source of supply.

Coil 5 is so designed that the frequency charv acteristics of theinductance thereof combined with the capacity of condenser 8 providesapproximately the lowest frequency at which it is desired to operate thetransmit- .ter. The high frequency energy may be transferred to anothercircuit by Inductance 13 which may be positioned in lnductive relationto said coil 5 and electrically associated with the load circuit 14.Load circuit 14 may comprise a space radio radiating-systerm, a wiredradio s stem or additional ther mionic tube ampli er circuit-s. Othercoupling arrangements may be employed such as causing contact members13"-13 to be corinected either directly or capacitively to coi 5.

When it is desired to operate the transmitter on a frequency higher thanthat obtained by employin coil 5 and capacity 8 alone, an auxiliary inuctance 11 is connected in parallel with coil 5 and capacity 8. This isaccomplished by closing switchmembers 9 and 10. Should coil 5' andinductance 11 have like frequency characteristics the resultant frequenccharacteristics when the two are connected in multiple would be thesum'of the two. Thus suppose the frequency characteristics of coil 5 andcapacity 8 were such as to give an oscillation constant of 50 and that Lwas 10 andG was 5. Assuming that the frequency characteristics ofinductance 11 were such as when employed with a capacity h'aving a valueof 5 would likewise give an oscillation constant of 50.. If theninductance 11 is connected in parallel relation with coil 5 I be had b'are employed in this illustration. The

anode circuits of thermionic tubes 1 and 2 are energized from source 16.Capacity 28 is connected to the mid-connection of coil 5 and to ground12. Inductance 11 is associated with space radio radiating system 12,12by coil 12. Coil 13 is provided by- ,which connections to a suitableload circuit may be had when different adjustments of frequency are notproperly related to the frequency characteristics of circuit 12, 12, 12The cathode circuits of thermionic tubes 1 .and 2 are energized fromtransformer 22 the latter of which is associated -with' any suitablesource of alternating current. Capacities 23 are provided as bypaths forhigh frequency energy to ground 12. A source of control electrodebiasing potential 17 supplies the proper potential to the respectivecontrol electrodes to insure the desire o erational characteristics.Thermionic tu es 1 and .2 are connected in an electrically balancedcircuit arrangement, inductance 18 and capacity 27 constituting theinput circuits and inductances 5-9 an capacity 8 constituting the outputcircuits.

' The circuits are electrically balanced by balancing condensers 20 and21 which pro vide means for counterbalancing or neutralizing unlikecharacteristics of the circuits. The input circuit of thermionic tubes 1and 2 are associated with any suitable source of high frequency encr 19by means of condensers 25 and 26. apacit 24 is provided to offer aby-path to the high frequency energy and exclude the same from source17.

Different adjustments in the frequency characteristics are obtained byopening or closing switch members 9 and 10.

Coil 5 comprises any suitable metal tubing and the inherent frequencycharacteristics of the inductance which it constitutes are not easilyadjusted. Since the opposite 'ends of the coil are connected to thesockets of the thermionic tubes" and a circulatory cooling liquid isflowing therethrough, it is obvious that it would be impractical toattempt to vary the length of the tubing. In the inductance system of myinvention the frequency characteristics of the circuit including 0011 5may be easily adjusted to any desired value without disturbing thecirculation of the cooling fluid.

I realize that many modifications of the inductance system of myinvention are possible without de arting from the spirit of myinvention. ny suitable type of'thermionictubes may be employed and anynumber of such tubes may be connected in suitable circuit arrangements.Similar inductances may be employed in the input circuit when a liquidcooled inductance is necessary or so desired. It is to be understoodthat my invention shall notbe restricted to precisely the arrangementsshown in the accompanying drawings or described in the foregoingspecification but only as defined by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is as follows:

1. An inductance system comprising in combination a metallic member ofhelical form providing a double passage for the circulation of liquidand means provided at the electrical center of the inductance wherebysaid liquid may be admitted to said passage.

2. An- -inductance system comprising a helix, said helix comprising'adouble passage for cooling fluids and a common passage for electricalenergy.

3. An inductance system comprising a helix, said helix comprising a dualpassage conductor for cooling fluids, a common passage for electricalenergy and connecting members provided at the electrical center of saidhelix for admitting said cooling fluids.

4. In an inductance system the combination of a helix, said helixcomprising metal tubing having a double passage for the circulation of acooling fluid and means provided at the electrical center of said helixfor admitting said fluid to said passages.

5. An inductance system comprising in combination a plurality of lengthsof metal tubing immediately adjacent to each other comprising a singleelectrical conductor and comprising a plurality of conductors for thecirculation of a liquid.

6. An inductance coil comprisin a helical formation of metallic tubingrovi ing a plurality of individual fluid con ucting passages immediatelyadjacent to each other and constituting a single electrical conductor.

7. An inductance coil comprising a helical formation of metallic tubinghaving a plu-' ralityof individual fluid conducting flpassages andasingle electrical passage, and uid connecting members associated withsaid coil at the electrical center thereof.

8. A high frequency inductance system comprisin tubing an means forassociating a cooling fluid with said tubing at the electrical center ofthe inductance.

LOUIS A. GEBHABD.

a helical formation of metallic

